Photoinduced Direct Conversion of Cyclohexane into Cyclohexanone Oxime using LEDs

Abstract

A selective direct photochemical transformation of cyclohexane into cyclohexanone oxime using tert‐butyl nitrite and UV LED diodes is described. The reaction allows the direct introduction of an oxime group into a hydrocarbon using a simple set‐up in one step that proceeds in a clean fashion, a transformation which technically would require several steps. This straightforward method may provide a valuable alternative to significantly more expensive common procedures for the synthesis of cyclohexanone oxime, a key precursor to the Nylon‐6 polymer.

Continuous generation, in-line quantification and utilization of nitrosyl chloride in photonitrosation reactions

“…This amount corresponds to a 66% yield for the photochemical step (with respect to NOCl), which agrees well with other methods published in the literature. 26 The overall yield of the process, using NaNO 2 as the limiting reagent, was 57%. 1 H NMR analysis of the product, with trichloroethylene as the internal standard, confirmed that the isolated solid was the hydrochloride salt of the oxime (see Fig.…”

“…10 Alternative photochemical methods using alkyl nitrites as nitrosyl radical sources have also been reported using UV light 25 and 365 nm or 405 nm LEDs. 26 The continuous flow setup consisted of the NOCl generator (described above), an additional reaction stream containing neat cyclohexane, and a continuous photochemical reactor (Fig. 7).…”

Catalytic Aerobic Oxidation of C(sp3)−H Bonds

“…[127] In the past, the activation of organic substrates was performed directly using high-energy UV radiation, which is less attractive. [129] However, there has been am ajor shift towards visible light photocatalysis.T his term might be somewhat misleading,a sthe photons themselves are not catalytic, but are used to bring ac atalyst to an excited state (called photocatalyst), which in turn activates the target substrate.Catalysts,either organic [130] or metal based, [131] are designed to absorb at wavelengths in the visible range of the spectrum. [129] However, there has been am ajor shift towards visible light photocatalysis.T his term might be somewhat misleading,a sthe photons themselves are not catalytic, but are used to bring ac atalyst to an excited state (called photocatalyst), which in turn activates the target substrate.Catalysts,either organic [130] or metal based, [131] are designed to absorb at wavelengths in the visible range of the spectrum.…”

Photochemical Flow Oximation of Alkanes

“…The absorption band responsible for the homolytic breaking of t-BuONO lies between 320-430 nm, but is partially overlapped, with the absorption band of the oxime product 3 and the dimer 5 which have a maximum at 300 nm but extends to around 360 nm. Wysocki et al 15 has shown that efficient activation of t-BuONO can be achieved using an emission between 365 and 405 nm and therefore a set of 365 nm LEDs were used. However, this does introduce some limitation regarding photon flux and can therefore lead to the requirement for longer reaction times to ensure high conversions.…”

“…To establish the flow process, we used cyclohexane and screened several molar ratios of reagents, temperature, and flow rates in order to find optimum conditions for the transformation. In their study, Wysocki et al 15 had determined that the addition of t-BuOH as an additive was highly beneficial to the reaction progress in batch. We therefore additionally wished to validate this finding with respect to the flow process (Table 1).…”